Incandescent wire ignition plug



' Oct. 9, 1934. G. WERNER AL 1,976,466

INCANDESCENT WIRE IGNITION PLUG Filed May 19. 1932 u III Patented. Oct. 9, 1934 INCANDESCENT WIRE IGNITION PLUG Gustav Werner and Karl Klelnert, Stuttgart,

Germany, assignors to Robert Bosch Aktiengesellschaft, Stuttgart, Germany Application May 19, 1932, Serial No. 612,347 In Germany May 29, 1931 5Clalms.

The present invention relates to incandescent wire ignition plugs.

In incandescent wire ignition plugs it frequently happens that the incandescent wire breaks owing to the vibrations of the engine. The breakage of the wire can be effectively avoided if the incandescent wire is made as stout as possible consistent with an ability to heat it by low voltage current. In known constructions the end of the wire is inserted in a hole bored in the centre of the inner end of the plug body. If the wire is comparatively thick, the wall of the plug body around the central electrode must be correspondingly thick so that the hole can be bored. In order that the plug body over the whole circumference shall not be of the.thickness necessary for the hole, according to the present invention the passage or bore for the middle electrode is so arranged that it lies eccentrically to the plug body at least at the end carrying the incandescent wire.

Two examples 01. construction of the invention are shown in the accompanying drawing, in which:--

Figure 1 is a sectional elevation of an incandescent wire ignition plug embodying this invention,

Figure 2 is a cross section on the line AB of Figure 1,

Figure 3 is a second construction, partly in section,

Figure 4 is a view of the plug from below, and

Figure 5 is an elevation of the incandescent wire in the direction of the arrow in Figure 4.

In the incandescent wire ignition plug a is a bore or passage b, which runs at a certain inclination to the axis of the plug a from the middle of the terminal end to the end carrying the incandescent wire. In the bore b is inserted the central electrode 0, which is surrounded by an insulating tube 12 and screwed into the terminal piece 6. an insulating disc I from the plug body. An incandescent wire it is secured in the end g of the central electrode, and the free end of the wire is anchored in a hole '1 in the plug body by weld- 1118.

In the second construction, the ends k 01' an incandescent wire are inserted into the plug body a. and into the central electrode 0 and connected to those parts by soldering or welding therewith. The incandescent wire has several helical coils m, the axis of which lies perpendicularly to the axis of the plug. The ends of the wire are carried tangentially to the coiled part of the wire and disposed approximately parallel to the axis of the ,plug. The convolutions oi the incandescent wire may be circular or oval.

As the ends of the incandescent wire are The terminal piece a is insulated by stretched straight, its resistance against breakage is very much increased.

We declare that what, we claim is:

1. An incandescent wire ignition plug comprising a metallic plug body having a bore, an electrode mounted in said bore and insulated from said body, and an incandescent wire the ends of which are secured to said body and electrode respectively, the bore of said body being eccentric so that the wall of said body at one side of the electrode is thinner than said wire and at the opposite side is at least as thick as said wire.

2. An incandescent wire ignition plug comprising a metallic plug body having a bore eccentric to at least the inner end of said plug, an electrode mounted in said bore and-insulated from said body, and an incandescent wire the ends of which are secured to said body and electrode, respectively, at diametrically opposite points closely adjacent the periphery of the inner end of said body.

3. An incandescent ignition plug comprising a metallic plug body having a bore therein extending from the center of the outer end of said body to a point eccentric to and closely adjacent the periphery of the inner end of said body, an electrode mounted in said bore and insulated from said body, and an incandescent wire the ends of which are secured to said body and electrode, respecirlvely, at diametrically opposite points closely adjacent the periphery of the inner end of said body.

4. An incandescent ignition plug comprising a plug body having a bore eccentric to at least the inner end of said plug, an electrode mounted in said bore and insulated from said body, and an ignition wire in the form of a.helix having a pair of ends which are straight and extend tangentially of the helix, said ends being secured to said body and electrode, respectively, at diametrically opposite points closely adjacent the periphery of the inner end of said body.

5. An incandescent ignition plug comprising a plug body having a bore eccentric to and closely adjacent the periphery of the inner end of said plug, an electrode mounted in said bore and insulated from said body, and an incandescent wire coil. the convolutions of which spread over substantially the entire area of the inner end of said body and the ends of which extend parallel to the axis of the plug and are secured to said body and electrode respectively at diametrically opposite points closely adjacent the periphery of the inner end of said body.

GUSTAV WERNER. KARL KLEINERT. 

